Portable electronic devices generally use internal rechargeable batteries for operation. In order to maintain the internal batteries in a state of charge, the device is generally recharged at regular intervals using a wall mains adaptor unit, whose function is to convert the comparatively high voltage AC mains voltage available at wall sockets, to a low voltage suitable for inputting to the device's charging input. At the same time, such a wall charger often regulates the charging profile to the internal batteries of the electronic device, in order to maximize charging efficiency, and to ensure safe charging. Other types of charger unit utilize the low voltage DC power source available in automobiles, such as the cigarette lighter socket, in order to charge the device's internal batteries. Such external power sources will be known as fixed power sources in this application. Furthermore, the term “wall charger” will generally be used in this application to include any type of charger which is generally plugged into a fixed power source.
However, an AC mains power source, or a car lighter socket, is not always available when the battery of the portable device requires charging, and the user then has to either carry with him spare charged batteries, which could be a safety hazard, or must purchase such batteries, which is not always a simple task, as many portable devices, and especially mobile phones, use dedicated battery packs which are not widely available. Even then, such battery packs are often supplied in a non-charged state.
One solution to this problem is described in U.S. Pat. No. 6,479,963, for “Rechargeable Battery Packs”, to the inventors of the present application, in which a novel battery pack is disclosed which can be fitted with a widely available primary cell to recharge the rechargeable cells of the portable device. Another solution is described in co-pending PCT Application published as International Patent Application No. WO/2006/095353 for “Portable Battery Operated Power Supply”, also to inventors of the present application, in which a special external battery pack, preferably containing a rechargeable cell, is used to enable recharging of the device at any location.
Each of these solutions has its own disadvantage. The former requires that the device be equipped with the special battery pack such as that described in the patent, while the latter requires of the device owner to carry with him/her the special external battery pack, and to ensure that the external battery pack is kept charged by connecting it to a conventional wall charger at the required intervals.
There therefore exists a need for a portable charging system which overcomes at least some of the disadvantages of prior art systems and methods, to enable the user of portable electronic devices to simply recharge the internal batteries of the device, without the need to have access to a fixed source of charging power.
Though the term battery is strictly speaking understood to mean a pack of at least two cells, in common usage the term is also understood to mean a single cell. Consequently, these two terms, battery and cell, may have been used interchangeably in this application, and may also have been thuswise claimed, and the number of cells in the device of the invention is not meant to be limited by use of one or the other term.
The disclosures of each of the publications mentioned in this section and in other sections of the specification, are hereby incorporated by reference, each in its entirety.